Conventionally, various methods have been proposed which display 3-dimensional images. There is a method called the “lenticular system” which is one of these. One example of a recording data format to be used in this lenticular system is disclosed in Japanese Patent Application Laid-open Hei 11-41627 described below.
FIG. 13 is a conceptual diagram showing one example of a data recording format of the lenticular system. A left-eye image 301 as shown in FIG. 13(a) and a right-eye image 302 as shown in FIG. 13(b) are each thinned to half with respect to the horizontal direction, forming and recording a frame of image 303 as shown in FIG. 13(c). The thus formed image that is composed of a plurality of images is called an integrated image. When reproduced, this integrated image 303 is rearranged in a format that corresponds to an associated display to perform stereoscopic display.
Since this integrated image can be handed as an ordinary 2-dimensional image, it is possible to compress the image using a predetermined compression technique, or store it in a predetermined file format. Upon this process, if a widespread compression technique and an existing file format are used, the integrated image can be recognized as an existing format file even in a conventional reproducing device having no 3-dimensional image displaying function and can be displayed as a 2-dimensional image. As the specific examples of compression methods and file formats, JPEG, BUMP, etc., can be given for still images while, for motion pictures, MPEG-1, MPEG-2, MPEG-4, MOTION JPEG, etc., can be given as the compression method and Quick Time, Real System, Windows (R) Media Video, etc., can be given as the file format.
From a viewpoint of performing display on conventional reproducing devices, when JPEG data is to be recorded, recording of data into files conforming to the Exif (Exchangeable image file format) and DCF (Design rule for Camera File system) standard, which is an image file format standard used for digital still cameras and related systems, makes it possible for the data to be reproduced on most digital still cameras. In this DCF standard, a file conforming to the DCF standard is called a DCT file and a directory for storing the DCF file is called a DCF directory; in order to establish strong compatibility between digital still cameras, the naming rules for DCF files and DCF directories are determined as follows.    (1) The name of a file is made of “filename”, “.” and “extension”.    (2) A filename is made of 8 characters.    (3) The first four characters of a filename can use any combination of half-width uppercase alphabetic characters, numerals and ‘ ’ (underbar).    (4) The last four characters of a filename forms a number between “0001” and “9999”, and is called a file number.    (5) A file containing a primary image is added with an extension “.JPG”.
The naming rules for DCF directories and the directory structure are as follows.    (1) A directory name is made of 8 characters.    (2) The first three characters of a directory name forms a number between “100” and “999”, and is called a directory number.    (3) The last five characters of a directory name can be any combination of half-width uppercase alphabetic characters, numerals and ‘ ’.    (4) DCF directories are formed under a directory titled as “DCIM” existing under the root directory.    (5) DCF files are stored under a DCF directory.
FIG. 14 shows an example of a directory structure conforming to the DCF standard.
When 3-dimensional image data is stored in an existing format, it is necessary to distinguish it from usual 2-dimensional image data as described above; one example of a method of distinction is disclosed in Japanese Patent Application Laid-open 2000-201308 described below.
In this disclosure, it is possible to collect special files into a particular directory by enabling the user to select the directory of the files to be recorded when images are captured by an electronic still camera.
However, even though the user recorded special files into the particular directory, it is impossible for another user to decide whether the files are of 3-dimensional image data or 2-dimensional image data.
Further, there are various information required for 3-dimensional display, such as the number of viewpoints, the method of thinning and others, it is however impossible to know in what format the recorded data was recorded, hence there occurs problem that, if a third person obtains the data, the person is not able to know how the data should be processed to display it.
The present invention has been devised to solve the above problems, it is therefore an object to provide an image file creating apparatus which enables distinction of a recorded image file between that of 2-dimensional image data and that of 3-dimensional image data as well as to providing an image file reproducing apparatus for reproducing such data.